Hypercatabolism in dialysis patients.
OBJECTIVE
This article will provide a comprehensive review and update on recent advances in the field of protein-energy wasting and protein kinetics in patients with end-stage renal disease.


RESULTS
Hypercatabolism in dialysis patients is related to intradialytic loss of amino acids as well as cytokine activation. Interleukin-6 pays a central role in regulating whole-body, muscle and hepatic protein turnover during hemodialysis. Amino acids released from the muscle protein catabolism are taken up by the liver for de-novo protein synthesis during hemodialysis. Intradialytic nutrient supplementation increases protein synthesis, but does not attenuate muscle protein catabolism.


CONCLUSIONS
Protein-energy wasting observed in end-stage renal disease is a maladaptive metabolic state, which often coexists with inflammation. Cytokine-adipokine signaling plays an important role in protein-energy wasting. Peripheral blood mononuclear cells and skeletal muscle are important sources of interleukin-6 during hemodialysis. In addition to contributing to intradialytic protein catabolism, interleukin-6 impairs effective utilization of amino acids for protein synthesis. Although muscle protein breakdown increases during hemodialysis, whole-body proteolysis is not increased. The dissociation between regional and whole-body protein kinetics in end-stage renal disease is due to somatic-hepatic recycling of amino acids. Net anabolism during hemodialysis may be achieved only by providing nutrients as well as inhibiting overt inflammatory signals.
Raj
Dominic S C
DS
Division of Nephrology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131-5271, USA. draj@salud.unm.edu
Sun
Yijuan
Y
Tzamaloukas
Antonios H
AH
D002100:Cachexia / Q000209:etiology / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004734:Energy Metabolism; D006801:Humans; D007333:Insulin Resistance; D007676:Kidney Failure, Chronic / Q000150:complications / Q000378:metabolism / Q000628:therapy*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D010288:Parenteral Nutrition; D011502:Protein-Energy Malnutrition / Q000209:etiology / Q000378:metabolism* / Q000628:therapy; D011506:Proteins / Q000378:metabolism*; D006435:Renal Dialysis / Q000009:adverse effects
D016207:Cytokines; D011506:Proteins